Background: Around 50% of patients with schizophrenia do not fully comply with treatment, and noncompliance is linked to relapse, rehospitalization, poor outcome, and high economic costs. The health belief model views noncompliance as a decision made by the patient, arrived at after weighing the perceived risks and benefits of treatment.

Data sources: A MEDLINE search for the years 1980-2002 using combinations of the keywords schizophrenia, compliance, adherence, antipsychotics, tolerability, and side effects was used to identify articles investigating the factors influencing compliance in schizophrenia.

Results: Many factors influence compliance, including those that affect patients' beliefs about their illness and the benefits of treatment (e.g., insight into illness, belief that medication can ameliorate symptoms), perceived costs of treatment (e.g., medication side effects), and barriers to treatment (e.g., ease of access to treatment, degree of family or social support). Medication side effects that are distressing to patients and linked to noncompliance include extrapyramidal side effects, neuroleptic dysphoria, akathisia, sexual dysfunction, and weight gain. Compliance can be improved by cognitive-behavioral therapies, such as compliance therapy, and other psychosocial interventions associated with improved social functioning and a lower risk of rehospitalization. Treatment adherence may also be improved by use of atypical antipsychotics with few perceived side effects.

Conclusion: By considering the factors leading to noncompliance and adopting a comprehensive strategy for improving compliance, encompassing psychosocial intervention and optimum choice of medication, the management of schizophrenia could be greatly improved.